The present invention relates to a tractor-trailer construction and specifically to a construction for over-the-road trailers used to carry bulk materials such as grain.
One problem encoutnered with present trailers of the type described above is the difficulty in distributing the weight of the cargo to the various axles of the vehicle in proportions which meet state and federal regulations while at the same time maximizing the cargo load being carried. This is particularly important in a tractor-trailer combination which utilizes a pair of tandem axles at the rear of the trailer, and a single axle at the rear of the tractor whicc pulls the trailer. Current regulations require that the weight on the tandem axle not exceed 34,000 pounds and that the weight on the single axle at the rear of the tractor not exceed 20,000 pounds.
Present trailers for carrying grain use a drop center configuration which centers the lowermost portion of the cargo bin equally between the rear tandem axles of the trailer and the rear single axle of the tractor. This causes the weight to be distributed nearly equally between the tandem axle at the rear of the trailer and the rear axle of the tractor. In the prior trailers, because the rear axle of the tractor has a maximum load limit of 20,000 pounds this maximum is met before the rear tandem axle achieves its maximum permissible limit of 34,000 pounds. Thus, in many present devices, the cargo carried by the trailer is substantially reduced due to the fact that the maximum 20,000 pound load limit of the rear tractor axle is achieved before the maximum 34,000 pound load limit for the rear tandem axle of the trailer.
Also, because of the various load limits permitted for each axle of the vehicle, it is desirable to minimize the weight of the trailer itself so that more weight can be utilized for the cargo which is being carried.
Most prior art trailers for carrying bulk materials utilize an inclined bottom wall having a drop center portion intermediate the opposite ends of the bottom wall. The bottom wall is welded at its sides to the sidewalls of the trailer. However, during the welding process, distortion occurs at the sidewalls of the trailer resulting in a less attractive appearance of the completed trailer. Another problem encountered with present trailers results from the twisting or distortion of the trailer as it passes over irregular terrains. The welding of the bottom wall of the trailer to the sidewalls of the trailer can cause distortion or damage to the sidewalls of the trailer as the trailer flexes while passing over irregular terrain.
Therefore a primary object of the present invention is the provision of an improved trailer construction.
A further object of the present invention is the provision of an improved trailer construction which permits distribution of the weight of the cargo in the trailer in such a manner as to maximize the amount of cargo which can be carried under various state and federal axle load requirements.
A further object of the present invention is the provision of an improved trailer construction which suspends the bottom wall of the cargo container from the upper edges of the sidewalls of the trailer so as to eliminate the need for welding the sides of the bottom wall to the sidewalls of the trailer.
A further object of the present invention is the provision of an improved trailer construction having a bottom wall which is curved in cross section so as to reduce the weight of the trailer.
A further object of the present invention is the provision of an improved trailer construction which utilizes a bottom wall of minimum weight and which does not require reinforcing members as in present trailer constructions.
A further object of the present invention is the provision of an improved trailer construction having a side discharge chute which will permit the contents of the trailer to be discharged into an auger conveyor. Prior hopper trailers require a drive over pit or an unloading auger having a swing auger or portable auger that can be moved underneath the trailer as the grain is discharged from the bottom of the trailer. With the side discharge chute of the present invention one can unload just by driving alongside of an auger conveyor. This makes the trailer more practical to use on a farm.
A further object of the present invention is the provision of an improved trailer construction which is economical to manufacture, durable in use, and efficient in operation.